1. Field of the Invention
The invention relates in general to electric power supplies and in particular to electric power supplies having two electrical battery storage means and an electrical generating means and switching means for independently charging and discharging each electrical battery storage means.
2. Description of the Related Art
Electric vehicles and other power supplies are dependent upon an electric battery storage means for operating energy. Generally, these consist of a `string` of storage batteries connected in series to achieve a suitable output operating voltage. In order to store a suitable amount of operating energy, the strings of series connected batteries are connected in parallel with one another to form a `battery pack` electric battery storage means. The batteries are interconnected by electric cables or rigid bus bars and are charged by flowing a charging current into the parallel connected strings from a suitable battery charger. The batteries are discharged by connecting the parallel strings to an electrical load such as a motor of the electric vehicle.
The battery packs described work well for their purpose, but they do have one inherent limitation. The commercially availabe battery packs do not have the electrical storage capacity to deliver an extended range for the electric vehicle. The related art has responded to this limitation by proposing `hybrid` vehicles that include an electrical generator powered by an internal combustion engine to recharge the battery pack during operation to increase the vehicle range. This solution is not favored by the motoring public or enviromentalist or the government, because the electric vehicle was proposed to replace the internal combustion engine driven vehicle.
Accordingly it would be desirable to have a means and method for extending the range of an electrical vehicle by in situ recharging the electrical storage capacity of commercially available battery packs while the vehicle is operating and without the use of an internal combustion engine driven generator. Such means and methods for in situ recharging the electrical storage capacity of commercially available battery packs should and would be just as applicable to portable power supplies for use in remote and emergency applications.
A search of the relevent art identified the following related references:
U.S. Pat. No. 3,962,621 is directed to a duel battery charging Generator system. The generator has two bridge rectifiers disposed within the frame of the generator. Each of these rectifiers is isolated from the other so that they may each charge a separate battery at the same time.
U.S. Pat. No. 4,043,293 is similar to '621 above in that both patents teach series connected batteries to obtain high voltage for starting. Both patents teach simultaneous charging of both batteries.
U.S. Pat. No. 4,516,066 disclosed another system for charging duel batteries.
U.S. Pat. No. 5,549,984 teaches a switching circuit for a primary/secondary battery system.
U.S. Pat. No. 5,666,006 is directed to a battery monitor and control system for preventing over charging and undercharging each battery in a string of batteries.
A thorough review of the above references reveals that none of the references teaches the methods and apparatus of the present invention of charging one battery pack while simultaneously discharging another battery pack in order to extend the total energy derived from the system.